This invention relates to an ignition system for a gas turbine engine, with each of the first and second ignition units being connected to first and second igniters and to a first and second power supply bus and a first and second control unit for the activation of power supply.
Ignition systems of the type specified above for the ignition of fuel fed to the combustion chamber of a gas turbine engine during engine start are generally known. While a single ignition unit and a single igniter would in principle be sufficient for starting, a combined system of two ignition units supplied with direct and alternating current from the aircraft and each connected to an igniter is installed for safety reasons and to satisfy all operating conditions, for example continuous ignition during extremely high humidity or re-start of an engine failed in service. Similarly, two control units are provided for electronic engine control, with each of the two electronic engine control units being connected to both ignition units to signal power supply from both control units to the ignition units, thus triggering the generation of the ignition voltage required for the ignition process. One power supply bus each is connected to the respective ignition unit for the provision of energy (P1 or P2, respectively).
The above described combined ignition system consisting of two ignition units and two igniters does, however, not operate with sufficient safety if power supply via the one or the other power supply bus to the respective ignition unit is not ensured for any reason.